In situ metal/ligand reactions under mild hydrothermal conditions which include oxidative C-C coupling and C-C cracking of 4,4'-trimethylene-dipyridine (TMDP) were discovered during the syntheses of two zinc titanophosphates referred to TiZn-1 and TiZn-2. Both structures are composed of four-ring layers formed of TiO6 octahedra and PO4 tetrahedra with pendant Zn tetrahedra being coordinated by organic ligands. The inorganic layers of TiZn-1 are interconnected by a dimeric form of TMDP, 1,2,4,5-tetra(4-pyridyl) benzene (TPB), via bis-monodentate coordination mode to zinc to form a neutral 3D framework. By increasing the amount of oxidizing reactant, however, pyridine-4-carboxylic acid (PCA) was generated from TMDP. In TiZn-2, the PCA acts as a monodentate ligand coordinated to zinc by its carboxylic group to form a 2D layer structure. TiZn-2 emits blue luminescence with exposure to 355 nm UV light. In our previous studies, we have prepared several TMDP-templated metal phosphates with intriguing white-light photoluminescence (PL). To further investigate the influence of TMDP on PL, the intercalation of TMDP into the layer structure was performed and characterized by powder X-ray diffraction. The PL of the intercalated compound shows not only the enhancement of intensity but also the emission wavelength shifted from blue to near-white-light.

Two zinc titanophosphates containing organic linkers from in situ metal/ligand reactions

253rd National Meeting (2017)

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